Inhibition of mediator and cytokine release from dispersed nasal polyp cells by terfenadine

The mechanism of action of H₁-blockers requires elucidation because they may possess properties unrelated to the blockage of histamine at its receptor level. A study was performed with enzymatically dispersed cells obtained from nasal polyps to examine the effect of terfenadine (0.1–10 μmol) on the release of leukotrienes (LT) (LTC₄/D₄ and LTB₄) after stimulation by anti-IgE, and on the spontaneous release of cytokines (granulocyte/macrophage-colony stimulating factor GM-CSF] and tumor necrosis factor-alpha TNF-α]) released from cells cultured for 6 h. Terfenadine inhibited significantly, and in a dose-dependent manner, the release of LTC₄/D₄, LTB₄, TNF-α, and GM-CSF. IC₅₀ values were determined for LTC₄/D₄ (8 μmol), LTB₄ (9.9 μmol), TNF-α (6.1 μmol), and GM-CSF (4 μmol). Terfenadine was found to possess new antiallergic properties with a novel in vitro model which mimics more closely inflammatory cells of allergic rhinitis or asthma.